WIP: Distributed RADAR-Docker stack

[yatharthranjan]

This breaks up the RADAR-base stack into different sets of components which can be deployed individually on separate hosts.

Some other changes from the single host RADAR-Docker:

• Updated to Confluent version 5.2.0
• Added Multi-host monitoring using Netdata.

Please see the README for more info.

TODO:

• configure Portainer for using multiple docker remotes.
• add a health check to commons for alerting.
• Abstract out the duplicate code shared in some components to /commons
• Add authentication to netdata.
• properly configure all the components to relay through the SMTP server provided.
• Add monitoring for HDFS and Data components.
• Add README file to each component for docs on component level usage and configuration.
• Investigate adding a separate instance of Nginx webserver to frontend and admin components so can still access if proxies component is down.
• Investigate adding a load balancer config to Nginx for stateless services like gateway, rest-proxy and schema-registry.